Recently various industries, such as the paper-making industry, are using wood chips produced from entire tree processing, as distinguished from those produced only from debarked logs. This has been possible since 1970 when the machine disclosed in U.S. Pat. No. 3,661,333 was introduced to reduce an entire tree with attached limbs and branches to chips. The tree reduction machine described in the patent produces a chip mixture which includes pieces of relatively small branches and twigs which are not in chip form, cards, and pieces of bark which may be referred to as overs, bark and leaf dust, and small chip pieces which may be referred to as fines, and chips, some with adhering bark, of a substantially uniform size which are useful in the paper-making and other industries. Previous efforts to resolve the problems involved with separating the wood chips from the remainder of the material have included the use of vibratory screen apparatus of the type disclosed in our co-pending application Ser. No. 236,032, filed Feb. 19, 1981, now U.S. Pat. No. 4,351,719.
The present system represents another approach to the separation which is required--which involves the augering of the chips across stationary, curvilinear, perforate surfaces at a controlled rate to achieve the separating action, as distinguished from the agitating of flat perforate surfaces. The system disclosed herein is particularly designed for large volume operations capable, for example, of processing more than one hundred tons of material per hour.
One of the prime objects of the present invention is to design a high-volume system which is extremely effective and difficult in separating the overs and the fines from the useable wood chips.
Another object of the invention is to design a machine of the character described which substantially scrubs off and pulverizes the softer adhering bark, but does not damage the chips--and efficiently processes the material so rapidly that processing costs are relatively minimal and great economies in these operations can be achieved.
Still another object of the invention is to provide a system which deposits the separated material in piles which can be readily removed in a high volume operation.